Can polyethylene passive samplers be used to measure infiltration?

Abstract

Environmental impact assessments on contaminated sites require to understand all of the possible sources of pollution in the field, including groundwater seepage. Polyethylene passive samplers have been used extensively to measure a chemical's concentration in the sediment or water column and conventional seepage meters are deployed to infer the infiltration flux. A model was developed to describe how passive samplers could instead realize both these functions to completely characterize contamination through seepage in the environment. The simulations describe the concentrations in a strip of polyethylene inserted in sediment where porewater flows steadily and vertically. Providing that the target chemical's diffusion and partitioning properties in the sediment are known, the model allows the user to obtain concentration profiles in the passive sampler at different infiltration velocities. Experimental data can then be fitted on these profiles to deduce infiltration within a factor of 2. The approach is promising and was successfully tested in the laboratory using naphthalene, and further studies should be made to fully validate the use of passive samplers as seepage meters.